Neuroprotective agents for the prevention and treatment of neurodegenerative diseases

ABSTRACT

Disclosed herein are methods of treating neurodegenerative diseases comprising administering to the subject a compound having the structure: wherein α and R1-R8 are described herein, or a compound having the structure: wherein Y, Z, and R21, R24, R25, and R31-R33 are described herein.

This application claims the benefit of U.S. Provisional Application No. 61/137,658, filed Aug. 1, 2008, the content of of which in its entirety is hereby incorporated by reference.

Throughout this application, certain publications are referenced. Full citations for these publications may be found immediately preceding the claims. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to describe more fully the state-of-the art to which this invention relates.

BACKGROUND OF THE INVENTION

It has been estimated that neurodegenerative diseases presently affect 20 million individuals worldwide. The cost for medical care of patients with Alzheimer's disease (AD), for example, was $91 billion in 2005 and is predicted to increase to $160 billion by 2010 (Burke 2007). Despite considerable research on the etiology and pharmacologic treatment of these diseases, no therapy is known to delay their progression (Schapira and Olanow 2004, Burke 2007). Recently, enhancing the activity of a ubiquitous regulatory protein Akt kinase has beneficial effects upon neurons of the substantia nigra of the midbrain of animals. The increased signaling of Akt mediates the improvement in the health of these neuronal cells in adult normal and aged neurons and confers almost complete protection against neurotoxin induced cell death in rodents (Ries et al, 2006).

AD and other neurodegenerative diseases are called tauopathies because they are characterized by the accumulation of aggregates of the tau protein in neurons. Tau proteins promote the assembly and stabilization of microtubular structures in neurons. The function of tau is regulated by phosphorylation at multiple serine and threonine sites (Sontag et al 1996; Tian and Wang 2002). The state of phosphorylation of tau influences its ability to bind to and enhance the polymerization of microtubules in neurons (Gong et al 2005; Meske et al 2008).

The basis by which increased Akt signaling produces neuroprotection is not certain (Burke 2007). It has been suggested that increased Akt signaling in neurons results in a decrease in the generation of deposits of neurofilaments within neurons leading to their dysfunction and eventual death (Gong et al, 2005. These filaments are composed of a structural protein called Tau. Tau proteins are susceptible to hyper-phosphorylation. Hyper-phosphorylation of tau proteins renders them inactive and results in their aggregation into paired helical filaments. These tangles of tau protein along with plaques of β-amyloid (AB) are the characteristic pathologic features of AD and the other tauopathies (Gong et al 2005).

Control of tau activity by phosphorylation is accomplished by several serine-threonine kinases, particularly glycogen synthase kinase-3β (GSK-3β). GSK-3β itself is regulated by other serine-threonine kinases especially Akt (Grimes and Jope 2001; Liu et al 2005). Activated (phosphorylated) Akt maintains GSK-3β in an inhibited (phosphorylated state). A decrease in Akt activity, that is reduced amounts of phosphorylated Akt, results in activation, that is, decreased phosphorylation of GSK-3β. Activated GSK-3β leads to hyper-phosphorylation of tau, which leads to neuronal cell death (Kaytor and Orr 2002; Baki et al 2008).

There is strong evidence from studies of human Alzheimer's disease and from a mouse model of Alzheimer's disease that failure of adequate levels of phosphorylation of GSK-3β by Akt results in hyper-phosphorylation of tau, generation of tau and amyloid plaques, and neuronal degeneration and death. In early onset familial AD (FAD) there is a defect in presenilins, trans-membrane proteins critical to normal development (Shen et al, 1997; Wong et al 1998). A member of this family, presenilin-1 (PS1), regulates PI3K/Akt signaling (Sherrington et al 1995; Baki et al 2004; Kang et al 2005; Uemura et al 2007). In primary neuronal cultures of cells from PS1 −/− mice, Baki et al (2008) showed that there was inadequate PI3K-Akt signaling resulting in decreased phosphorylation of GSK-3β, hyper-phosphorylation of tau, and progressive neurodegeneration. The addition of normal presenilin-1 or of PI3K-Akt increased GSK-3β phosphorylation and suppressed neuronal cell death.

Ries et al. (2006) showed that increasing the concentration of activated Akt inhibits cell death of dopamine neurons of the substantia nigra in mouse model of Parkinson's disease induced by 6-hydroxy dopamine. Increasing Akt activity in the brain of normal adult and also aged mice enhanced the integrity and function of existing dopamine neurons (Ries et al., 2006). In a mouse model of AD, animals with genetically engineered increased amounts of GSK-3β in the forebrain have all the histologic and, to the extent that they can be assessed in the mouse, functional defects of human AD. Elimination of over-expression of GSK-3β by suppression of the transgene results in a return toward normal of all histologic and functional signs of AD (Engel et al 2006).

Neurodegenerative diseases such as AD are frequently characterized by impaired learning and memory. The mechanism(s) responsible for these most troublesome symptoms are associated with death of neuronal cells. At a molecular level, the basis for changes in memory formation and consolidation has been linked to the activity of histone deacetylases chromatin structures (Korzus et al, 2004; Levenson et al, 2004). Beglopoulos and Shen (2006) found that inhibitors of phosphodiesterase 4 and histone deacetylases reduce memory deficits and neurodegeneration in animal models of AD affecting cAMP response element (CRE) genes. Recently, Fischer et al (2007) reported improved learning behavior and access to long-term memories after significant neuronal loss and brain atrophy can be reestablished in a mouse model by environmental enrichment and by treatment with inhibitors of histone deacetylases (see reviews and commentaries by Sweat, 2007; Mangan and Levenson 2007; Albert 2007; Abel and Zukin; 2008).

Acetylation and deacetylation have a critical role in regulation of gene expression, cellular proliferation, development and differentiation, with aberrant deacetylation leading to a multitude of disorders (Abel and Zukin, 2008). Histone deacetylase inhibitors (HDACi) have anti-inflammatory and neuroprotective effects in models of stroke and Alzheimer's disease (AD) (Abel and Zukin, 2008). Inhibitors of protein phosphatase 2A (PP2Ai), primarily the shellfish toxin, okadaic acid, have neuroprotective effects in some model systems but are injurious in others (Tian and Wang, 2002).

Thus, there is substantial evidence that AD is a pathologic condition resulting from inadequate activity of the enzyme Akt and excessive activity of GSK-3β and that reduction of GSK-3β activity may reduce the severity of precipitated tau proteins, with a lessening of neurological deficit. In addition, there appears to be a poorly understood component of neurodegenerative diseases related to excessive histone deacetylase activity, or at least a condition of reduced acetylation of certain histones that is corrected by increased acetylation resulting in improved learning and memory. Non-toxic drugs that protect and foster the survival of acute and chronically diseased neurons are urgently needed.

The compounds described herein reduce the activity of GSK-3β and increase the acetylation of neuronal histones.

SUMMARY OF THE INVENTION

This invention disclosed herein provides a method of treating a subject with a neurodegenerative disease comprising administering to the subject a compound having the structure

wherein bond α is present or absent; R₁ and R₂ is each independently H, O⁻ or OR₉, where R₉ is H, alkyl, alkenyl, alkynyl or aryl, or R₁ and R₂ together are ═O; R₃ and R₄ are each different, and each is OH, O⁻, OR₉, SH, S⁻, SR₉,

where X is O, S, NR₁₀, or N⁺R₁₀R₁₀, where each R₁₀ is independently H, alkyl, substituted C₂-C₁₂ alkyl, alkenyl, substituted C₄-C₁₂ alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl where the substituent is other than chloro when R₁ and R₂ are ═O,

-   -   —CH₂CN, —CH₂CO₂R₁₁, —CH₂COR₁₁, —NHR₁₁ or —NH⁺(R₁₁)₂, where each         R₁₁ is independently alkyl, alkenyl or alkynyl, each of which is         substituted or unsubstituted, or H; R₅ and R₆ is each         independently H, OH, or R₅ and R₆ taken together are ═O; and R₇         and R₈ is each independently H, F, Cl, Br, SO₂Ph, CO₂CH₃, or         SR₁₂, where R₁₂ is H, aryl or a substituted or unsubstituted         alkyl, alkenyl or alkynyl, or a salt, enantiomer or zwitterion         of the compound, or a compound having the structure

wherein n is 1-10; Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂, trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl; Z is

R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl; R₂₄ is OH or SH; and R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl, SO₂R₃₄, NO₂, trifluoromethyl, methoxy, or CO—R₃₄, wherein R₃₄ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl, or a salt of the compound, in an amount effective to treat the subject.

This invention also provides a method for reducing the amount of GSK-3β in a neural cell comprising contacting the cell with an effective amount of a compound having the structure

wherein bond α is present or absent; R₁ and R₂ is each independently H, O⁻ or OR₉, where R₉ is H, alkyl, alkenyl, alkynyl or aryl, or R₁ and R₂ together are ═O; R₃ and R₄ are each different, and each is OH, O⁻, OR₉, SH, S⁻, SR₉,

where X is O, S, NR₁₀, or N⁺R₁₀R₁₀, where each R₁₀ is independently H, alkyl, substituted C₂-C₁₂ alkyl, alkenyl, substituted C₄-C₁₂ alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl where the substituent is other than chloro when R₁ and R₂ are ═O,

-   -   —CH₂CN, —CH₂CO₂R₁₁, —CH₂COR₁₁, —NHR₁₁ or —NH⁺(R₁₁)₂, where each         R₁₁ is independently alkyl, alkenyl or alkynyl, each of which is         substituted or unsubstituted, or H; R₅ and R₆ is each         independently H, OH, or R₅ and R₆ taken together are ═O; and R₇         and R₈ is each independently H, F, Cl, Br, SO₂Ph, CO₂CH₃, or         SR₁₂, where R₁₂ is H, aryl or a substituted or unsubstituted         alkyl, alkenyl or alkynyl,or a salt, enantiomer or zwitterion of         the compound, or a compound having the structure

wherein n is 1-10; Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂, trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl; Z is

R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl; R₂₄ is OH or SH; and R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl, SO₂R₃₄, NO₂, trifluoromethyl, methoxy, or CO—R₃₄, wherein R₃₄ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl, or a salt of the compound, so as to thereby reduce the amount of GSK-3β in the neural cell.

Also provided is a method for increasing the amount of phosphorylated Akt in a neural cell comprising contacting the neural cell with an effective amount of a compound having the structure

wherein bond α is present or absent; R₁ and R₂ is each independently H, O⁻ or OR₉, where R₉ is H, alkyl, alkenyl, alkynyl or aryl, or R₁ and R₂ together are ═O; R₃ and R₄ are each different, and each is OH, O⁻, OR₉, SH, S⁻, SR₉,

where X is O, S, NR₁₀, or N⁺R₁₀R₁₀ where each R₁₀ is independently H, alkyl, substituted C₂-C₁₂ alkyl, alkenyl, substituted C₄-C₁₂ alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl where the substituent is other than chloro when R₁ and R₂ are ═O,

—CH₂CN, —CH₂CO₂R₁₁, —CH₂COR₁₁, —NHR₁₁ or —NH⁺(R₁₁)₂, where each R₁₁ is independently alkyl, alkenyl or alkynyl, each of which is substituted or unsubstituted, or H; R₅ and R₆ is each independently H, OH, or R₅ and R₆ taken together are ═O; and

-   -   R₇ and R₈ is each independently H, F, Cl, Br, SO₂Ph, CO₂CH₃, or         SR₁₂, where R₁₂ is H, aryl or a substituted or unsubstituted         alkyl, alkenyl or alkynyl,or a salt, enantiomer or zwitterion of         the compound, or a compound having the structure

wherein n is 1-10; Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂, trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl; Z is

R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl; R₂₄ is OH or SH; and R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl, SO₂R₃₄, NO₂, trifluoromethyl, methoxy, or CO—R₃₄, wherein R₃₄ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl, or a salt of the compound, so as to thereby increase the amount of phosphorylated Akt in the neural cell.

This invention further provides a method for reducing the phosphorylation of tau in a neural cell, comprising contacting the neural cell with an effective amount of a compound having the structure

wherein bond α is present or absent; R₁ and R₂ is each independently H, O⁻or OR₉, where R₉ is H, alkyl, alkenyl, alkynyl or aryl, or R₁ and R₂ together are ═O; R₃ and R₄ are each different, and each is OH, O⁻, OR₉, SH, S⁻, SR₉,

where X is O, S, NR₁₀, or N⁺R₁₀R₁₀, where each R₁₀ is independently H, alkyl, substituted C₂-C₁₂ alkyl, alkenyl, substituted C₄-C₁₂ alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl where the substituent is other than chloro when R₁ and R₂ are ═O,

-   -   —CH₂CN, —CH₂CO₂R₁₁, —CH₂COR₁₁, —NHR₁₁ or —NH⁺(R₁₁)₂, where each         R₁₁ is independently alkyl, alkenyl or alkynyl, each of which is         substituted or unsubstituted, or H; R₅ and R₆ is each         independently H, OH, or R₅ and R₆ taken together are ═O; and R₇         and R₈ is each independently H, F, Cl, Br, SO₂Ph, CO₂CH₃, or         SR₁₂, where R₁₂ is H, aryl or a substituted or unsubstituted         alkyl, alkenyl or alkynyl, or a salt, enantiomer or zwitterion         of the compound, or a compound having the structure

wherein n is 1-10; Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂, trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl; Z is

R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl; R₂₄ is OH or SH; and R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl, SO₂R₃₄, NO₂, trifluoromethyl, methoxy, or CO—R₃₄, wherein R₃₄ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl, or a salt of the compound, so as to thereby reduce the phosphorylation of tau in the neural cell.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1: Induction of phosphorylated Akt by Compound 100 in DAOY cells in culture.

-   -   The medulloblastoma cells, DAOY, in culture were exposed to         Compound 100, Compound 205 or vehicle alone. After 4 hours         western blots were made for p-Akt, total Akt, and beta actin.         Control cells (C) showed only trace amounts of p-Akt and         substantial amounts of total Akt and beta actin. Exposure to         Compound 205, a compound with no anti-PP2A activity, had no         effect. Exposure to Compound 100 revealed induction of p-Akt and         an increase in total Akt relative to beta actin.

FIG. 2: Induction of phosphorylated Akt by Compound 100 in DAOY cells growing as xenografts in SCID mice.

-   -   SCID mice with human medulloblastoma cells, DAOY, implanted         subcutaneously were treated with 0.03 mg/20 gram mouse with         Compound 100 or vehicle alone. After 4 hours and 24 hours         western blots were made for p-Akt, total Akt, and beta actin.         Control cells (C) at both time points (only 24 hour point shown)         had only trace amounts of p-Akt and substantial amounts of total         Akt and beta actin. Exposure to Compound 100 revealed induction         of p-Akt and an increase in total Akt relative to beta actin.

FIG. 3: Induction of phosphorylated Akt by Compound-100 in U87 cells in culture.

-   -   The human glioblastoma cells, U87, were exposed to compound 100         or vehicle alone. After 4 hours western blots were made for         p-Akt, total Akt, and beta actin. Control cells (C) showed only         trace amounts of p-Akt and substantial amounts of total Akt and         beta actin. Exposure to Compound 100 revealed induction of p-Akt         and an increase in total Akt relative to beta actin.

FIG. 4: Induction of phosphorylated Akt by Compound-100 in U87 cells growing as xenografts in SCID mice.

-   -   SCID mice with human glioblastoma cells, U87, implanted         subcutaneously were treated with 0.03 mg/20 gram mouse with         Compound 100 or vehicle alone. After 4 hours, western blots were         made for p-Akt, total Akt, and beta actin. Control cells (C)         showed only trace amounts of p-Akt and substantial amounts of         total Akt and beta actin. Exposure to Compound 100 revealed         induction of p-Akt and an increase in total Akt relative to beta         actin.

FIG. 5: Induction of acetylation of Histone 3 and Histone 4 in normal mouse brain by Compound 100 and Compound 102.

-   -   Normal mice were treated with Compound 100 and Compound 102,         0.03 mg/20 gram mouse. After 4 hours of exposure, treated and         control animals (vehicle alone) animals were sacrificed and         western blots for acetylated histone 3 and histone 4 were made.         Both drugs increased acetylation of the histones compared to         control tissue.

FIG. 6. Photomicrographs of primary embryonal rat cortical neuronal cells at 23 days subjected to environmental stress by exposure to growth factor deficient medium for 1 hour on day 3 of culture.

FIG. 7. Average number of primary embryonal rat cortical neuronal cells at 3, 6, 13, and 23 days in culture (n=4).

-   -   All cultures were exposed to growth factor deficient medium for         1 hour on day 3 followed by of culture in complete medium         containing no supplement (control), drug vehicle (0.05% DMSO),         compound 102 (500 nM), or compound 201 (500 nM). Only exposure         to compound 201 resulted in statistically significant (p<=0.01)         protection of cell integrity.

FIGS. 8-10. Calcium response to acute exposure of 200 uM glutamate in the presence of vehicle (0.05% DMSO).

-   -   FIG. 8 shows photomicrographs of one field of cells in which         change in calcium flux was measured in individual cells (FIG.         9), and then averaged (FIG. 10).

FIGS. 11-14. Calcium response to acute exposure to 200 uM glutamate in the presence of 500 nm Compound 102.

-   -   FIG. 11 shows photomicrographs of one field of cells in which         change in calcium flux was measured in individual cells (FIG.         12), then averaged (FIG. 13), and the average response was         compared to the DMSO control (FIG. 14). The presence of compound         102 significantly enhanced the response to glutamate (p<=0.001)         in this particular study.

FIGS. 15-18. Calcium response to acute exposure to 200 uM glutamate in the presence of 500 nm Compound 201.

-   -   FIG. 15 shows photomicrographs of one field of cells in which         change in calcium flux was measured in individual cells (FIG.         16), then averaged (FIG. 17), and the average response was         compared to the DMSO control (FIG. 18). The presence of compound         201 significantly enhanced the response to glutamate (p<=0.001)         in this particular study.

FIG. 19. Bar graph showing the average % increase in response to glutamate exposure of 4 separate experiments.

-   -   Compound 201 significantly enhanced the response to glutamate         (p<=0.001) whereas compound 102 was less effective but still had         a significant effect of the response at p<=0.01

DETAILED DESCRIPTION OF THE INVENTION Embodiments

This invention provides a method of treating a subject with a neurodegenerative disease comprising administering to the subject a compound having the structure

-   -   wherein     -   bond α is present or absent;     -   R₁ and R₂ is each independently H, O⁻ or OR₉,         -   where R₉ is H, alkyl, alkenyl, alkynyl or aryl, or R₁ and R₂             together are ═O;     -   R₃ and R₄ are each different, and each is OH, O⁻, OR₉, SH, S⁻,         SR₉,

-   -   where X is O, S, NR₁₀, or N⁺R₁₀R₁₀,         -   where each R₁₀ is independently H, alkyl, substituted C₂-C₁₂             alkyl, alkenyl, substituted C₄-C₁₂ alkenyl, alkynyl,             substituted alkynyl, aryl, substituted aryl where the             substituent is other than chloro when R₁ and R₂ are ═O,

-   -   -   —CH₂CN, —CH₂CO₂R₁₁, —CH₂COR₁₁, —NHR₁₁ or —NH⁺(R₁₁)₂, where             each R₁₁ is independently alkyl, alkenyl or alkynyl, each of             which is substituted or unsubstituted, or H;         -   R₅ and R₆ is each independently H, OH, or R₅ and R₆ taken             together are ═O; and         -   R₇ and R₈ is each independently H, F, Cl, Br, SO₂Ph, CO₂CH₃,             or SR₁₂,             -   where R₁₂ is H, aryl or a substituted or             -   unsubstituted alkyl, alkenyl or alkynyl, or a salt,                 enantiomer or zwitterion of the compound, or a compound                 having the structure

-   -   wherein     -   n is 1-10;     -   Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂,         trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl;     -   z is

-   -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently     -   H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F,     -   Cl, SO₂R₃₄, NO₂, trifluoromethyl, methoxy, or CO—R₃₄, wherein     -   R₃₄ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl, or a         salt of the compound,     -   in an amount effective to treat the subject.

In an embodiment of the above method, the compound has the structure

-   -   wherein     -   n is 1-9;     -   Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂,         trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl,         SO₂R₃₄, NO₂, trifluoromethyl, methoxy, or CO—R₃₄, wherein R₃₄ is         alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl.

In another embodiement of the above method, the compound has the structure

-   -   wherein     -   n is 1-8;     -   Y is CH or N;     -   R₂₀ is H or OH;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         C₁-C₆ alkyl or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂, trifluoromethyl, methoxy,         or CO—R₂₆, wherein R₂₆ is alkyl, alkenyl, alkynyl, C₃-C₈         cycloalkyl, or aryl.

In a further embodiment of the above method, the compound has the structure

-   -   wherein     -   n is 1-9;     -   Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂,         trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently     -   H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and         R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl,         trifluoromethyl, methoxy, or CO—R₃₄, wherein R₃₄ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl; In further         embodiment, the compound has the structure

-   -   wherein     -   n is 1-8;     -   Y is CH or N;     -   R₂₀ is H or OH;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         C₁-C₆ alkyl or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅ is H, OH, SH, F, Cl, trifluoromethyl, methoxy, or CO—R₂₆,         wherein R₂₆ is alkyl, alkenyl, alkynyl, or C₃-C₈ cycloalkyl, or         aryl.

In another embodiment, the compound has the structure

-   -   wherein     -   n is 1-8;     -   Y is CH or N;     -   R₂₀ is H or OH;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         C₁-C₆ alkyl or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅ is H, OH, SH, F, Cl, trifluoromethyl, methoxy, or CO—R₂₆,         wherein R₂₆ is alkyl, alkenyl, alkynyl, or C₃-C₈ cycloalkyl, or         aryl.

In an embodiment of the above method, subject is a mammal.

In another embodiment of the above method, the neurodegenerative disease is Alzheimer's disease, Mild Cognitive Impairment, Parkinsons Disease, Frontotemporal Dementia, Dementia, or Lewy Body Dementia. In a further embodiment the neurodegenerative disease is Alzheimer's disease.

Another embodiment of the above method further comprises administering to the subject an NMDA receptor antagonist, an acetylcholinesterase inhibitor, an anti-amyloid antibody, a 5-HT6 antagonist, a gamma secretase inhibitor, a beta secretase inhibitor, or an inhibitor of aggregation of amyloid-β peptide. In another embodiment, the method further comprises administering to the subject a tau aggregation inhibitor.

Examples of known NMDA receptor agonists include, but are not limited to, memantine. Examples of known acetylcholinesterase inhibitors include, but are not limited to, galantamine, rivastigmine, and donapezil. Examples of a tau aggregation inhibitor include, but are not limited to, rember.

In another embodiment of the above method, the neurodegenerative disease is Parkinson's disease.

Another embodiment of the above method further comprises administering to the subject a dopamine receptor agonist.

The invention provides a method for reducing the amount of active GSK-3B in a neural cell comprising contacting the cell with an effective amount of a compound having the structure

-   -   wherein     -   bond α is present or absent;     -   R₁ and R₂ is each independently H, O⁻ or OR₉,         -   where R₉ is H, alkyl, alkenyl, alkynyl or aryl, or R₁ and R₂             together are ═O;     -   R₃ and R₄ are each different, and each is OH, O⁻, OR₉, SH, S⁻,         SR₉,

-   -   where X is O, S, NR₁₀, or N⁺R₁₀R₁₀,         -   where each R₁₀ is independently H, alkyl, substituted C₂-C₁₂             alkyl, alkenyl, substituted C₄-C₁₂ alkenyl, alkynyl,             substituted alkynyl, aryl, substituted aryl where the             substituent is other than chloro when R₁ and R₂ are ═O,

-   -   -   —CH₂CN, —CH₂CO₂R₁₁, —CH₂COR₁₁, —NHR₁₁ or —NH⁺(R₁₁)₂, where             each R₁₁ is independently alkyl, alkenyl or alkynyl, each of             which is substituted or unsubstituted, or H;

    -   R₅ and R₆ is each independently H, OH, or R₅ and R₆ taken         together are ═O; and

    -   R₇ and R₈ is each independently H, F, Cl, Br, SO₂Ph, CO₂CH₃, or         SR₁₂,         -   where R₁₂ is H, aryl or a substituted or unsubstituted             alkyl, alkenyl or alkynyl,

    -   or a salt, enantiomer or zwitterion of the compound, or a         compound having the structure

-   -   wherein     -   n is 1-10;     -   Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂,         trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl;

-   -   z is     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl,         SO₂R₃₄, NO₂, trifluoromethyl, methoxy, or CO—R₃₄, wherein     -   R₃₄ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl, or a         salt of the compound,

so as to thereby reduce the amount of GSK-3B in the neural cell.

In an embodiment of the above method, the compound has the structure

-   -   wherein     -   n is 1-9;     -   Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂,         trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl,         SO₂R₃₄, NO₂, trifluoromethyl, methoxy, or CO—R₃₄, wherein     -   R₃₄ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl.

In another embodiement of the above method, the compound has the structure

-   -   wherein     -   n is 1-8;     -   Y is CH or N;     -   R₂₀ is H or OH;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         C₁-C₆ alkyl or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂, trifluoromethyl, methoxy,         or CO—R₂₆, wherein R₂₆ is alkyl, alkenyl, alkynyl, C₃-C₈         cycloalkyl, or aryl.

In a further embodiment of the above method, the compound has the structure

-   -   wherein     -   n is 1-9;     -   Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂,         trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl,         trifluoromethyl, methoxy, or CO—R₃₄, wherein R₃₄ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl; In further         embodiment, the compound has the structure

-   -   wherein     -   n is 1-8;     -   Y is CH or N;     -   R₂₀ is H or OH;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         C₁-C₆ alkyl or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅ is H, OH, SH, F, Cl, trifluoromethyl, methoxy, or CO—R₂₆,         wherein R₂₆ is alkyl, alkenyl, alkynyl, or C₃-C₈ cycloalkyl, or         aryl.

In another embodiment, the compound has the structure

-   -   wherein     -   n is 1-8;     -   Y is CH or N;     -   R₂₀ is H or OH;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         C₁-C₆ alkyl or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅ is H, OH, SH, F, Cl, trifluoromethyl, methoxy, or CO—R₂₆,         wherein R₂₆ is alkyl, alkenyl, alkynyl, or C₃-C₈ cycloalkyl, or         aryl.

The invention provides a method for increasing the amount of phosphorylated Akt in a neural cell comprising contacting the neural cell with an effective amount of a compound having the structure

-   -   wherein     -   bond α is present or absent;     -   R₁ and R₂ is each independently H, O⁻ or OR₉,         -   where R₉ is H, alkyl, alkenyl, alkynyl or aryl, or R₁ and R₂             together are ═O;     -   R₃ and R₄ are each different, and each is OH, O⁻, OR₉, SH, S⁻,         SR₉,

-   -   where X is O, S, NR₁₀, or N⁺R₁₀R₁₀,         -   where each R₁₀ is independently H, alkyl, substituted C₂-C₁₂             alkyl, alkenyl, substituted C₄-C₁₂ alkenyl, alkynyl,             substituted alkynyl, aryl, substituted aryl where the             substituent is other than chloro when R₁ and R₂ are ═O,

-   -   -   —CH₂CN, —CH₂CO₂R₁₁, —CH₂COR₁₁, —NHR₁₁ or —NH⁺(R₁₁)₂, where             each R₁₁ is independently alkyl, alkenyl or alkynyl, each of             which is substituted or unsubstituted, or H;

    -   R₅ and R₆ is each independently H, OH, or R₅ and R₆ taken         together are ═O; and

    -   R₇ and R₈ is each independently H, F, Cl, Br, SO₂Ph, CO₂CH₃, or         SR₁₂,         -   where R₁₂ is H, aryl or a substituted or unsubstituted             alkyl, alkenyl or alkynyl,

    -   or a salt, enantiomer or zwitterion of the compound, or a         compound having the structure

-   -   wherein     -   n is 1-10;     -   Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂,         trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl;     -   z is

-   -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl,         SO₂R₃₄, NO₂, trifluoromethyl, methoxy, or CO—R₃₄, wherein     -   R₃₄ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl, or a         salt of the compound,         so as to thereby increase the amount of phosphorylated Akt in         the neural cell.

In an embodiment of the above method, the compound has the structure

-   -   wherein     -   n is 1-9;     -   Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂,         trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl,         SO₂R₃₄, NO₂, trifluoromethyl, methoxy, or CO—R₃₄, wherein     -   R₃₄ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl.

In another embodiement of the above method, the compound has the structure

-   -   wherein     -   n is 1-8;     -   Y is CH or N;     -   R₂₀ is H or OH;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         C₁-C₆ alkyl or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂, trifluoromethyl, methoxy,         or CO—R₂₆, wherein R₂₆ is alkyl, alkenyl, alkynyl, C₃-C₈         cycloalkyl, or aryl.

In a further embodiment of the above method, the compound has the structure

-   -   wherein     -   n is 1-9;     -   Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂,         trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and         R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl,         trifluoromethyl, methoxy, or CO—R₃₄, wherein R₃₄ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl; In further         embodiment, the compound has the structure

-   -   wherein     -   n is 1-8;     -   Y is CH or N;     -   R₂₀ is H or OH;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         C₁-C₆ alkyl or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅ is H, OH, SH, F, Cl, trifluoromethyl, methoxy, or CO—R₂₆,         wherein R₂₆ is alkyl, alkenyl, alkynyl, or C₃-C₈ cycloalkyl, or         aryl.

In another embodiment, the compound has the structure

-   -   wherein     -   n is 1-8;     -   Y is CH or N;     -   R₂₀ is H or OH;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         C₁-C₆ alkyl or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅ is H, OH, SH, F, Cl, trifluoromethyl, methoxy, or CO—R₂₆,         wherein R₂₆ is alkyl, alkenyl, alkynyl, or C₃-C₈ cycloalkyl, or         aryl.

The invention provides a method for reducing the phosphorylation of Tau protein in a cell, comprising contacting the cell with an effective amount of a compound having the structure

-   -   wherein     -   bond α is present or absent;     -   R₁ and R₂ is each independently H, O⁻ or OR₉,         -   where R₉ is H, alkyl, alkenyl, alkynyl or aryl, or R₁ and R₂             together are ═O;     -   R₃ and R₄ are each different, and each is OH, O⁻, OR₉, SH, S³¹ ,         SR₉,

-   -   where X is O, S, NR₁₀, or N⁺R₁₀R₁₀,         -   where each R₁₀ is independently H, alkyl, substituted C₂-C₁₂             alkyl, alkenyl, substituted C₄-C₁₂ alkenyl, alkynyl,             substituted alkynyl, aryl, substituted aryl where the             substituent is other than chloro when R₁ and R₂ are ═O,

-   -   -   —CH₂CN, —CH₂CO₂R₁₁, —CH₂COR₁₁, —NHR₁₁ or —NH⁺(R₁₁)₂, where             each R₁l is independently alkyl, alkenyl or alkynyl, each of             which is substituted or unsubstituted, or H;

    -   R₅ and R₆ is each independently H, OH, or R₅ and R₆ taken         together are ═O; and

    -   R₇ and R₈ is each independently H, F, Cl, Br, SO₂Ph, CO₂CH₃, or         SR₁₂,         -   where R₁₂ is H, aryl or a substituted or unsubstituted             alkyl, alkenyl or alkynyl,

    -   or a salt, enantiomer or zwitterion of the compound, or a         compound having the structure

-   -   wherein     -   n is 1-10;     -   Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂,         trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl;     -   z is

-   -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl,         SO₂R₃₄, NO₂, trifluoromethyl, methoxy, or CO—R₃₄, wherein     -   R₃₄ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl, or         a salt of the compound,so as to thereby reduce the         phosphorylation of tau in the cell.

In an embodiment of the above method, the compound has the structure

-   -   wherein     -   n is 1-9;     -   Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂,         trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl,         SO₂R₃₄, NO₂, trifluoromethyl, methoxy, or CO—R₃₄, wherein     -   R₃₄ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl.

In another embodiement of the above method, the compound has the structure

-   -   wherein     -   n is 1-8;     -   Y is CH or N;     -   R₂₀ is H or OH;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         C₁-C₆ alkyl or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂, trifluoromethyl, methoxy,         or CO—R₂₆, wherein R₂₆ is alkyl, alkenyl, alkynyl, C₃-C₈         cycloalkyl, or aryl.

In a further embodiment of the above method, the compound has the structure

-   -   wherein     -   n is 1-9;     -   Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂,         trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and         R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl,         trifluoromethyl, methoxy, or CO—R₃₄, wherein R₃₄ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl; In further         embodiment, the compound has the structure

-   -   wherein     -   n is 1-8;     -   Y is CH or N;     -   R₂₀ is H or OH;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         C₁-C₆ alkyl or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅ is H, OH, SH, F, Cl, trifluoromethyl, methoxy, or CO—R₂₆,         wherein R₂₆ is alkyl, alkenyl, alkynyl, or C₃-C₈ cycloalkyl, or         aryl.

In another embodiment, the compound has the structure

-   -   wherein     -   n is 1-8;     -   Y is CH or N;     -   R₂₀ is H or OH;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         C₁-C₆ alkyl or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅ is H, OH, SH, F, Cl, trifluoromethyl, methoxy, or CO—R₂₆,         wherein R₂₆ is alkyl, alkenyl, alkynyl, or C₃-C₈ cycloalkyl, or         aryl.

The invention provides a method for reducing the aggregation of Tau protein in a cell comprising contacting the cell with an effective amount of a compound having the structure

-   -   wherein     -   bond α is present or absent;     -   R₁ and R₂ is each independently H, O⁻ or OR₉,         -   where R₉ is H, alkyl, alkenyl, alkynyl or aryl, or R₁ and R₂             together are ═O;     -   R₃ and R₄ are each different, and each is OH, O⁻, OR₉, SH, S⁻,         SR₉,

-   -   where X is O, S, NR₁₀, or N⁺R₁₀R₁₀,         -   where each R₁o is independently H, alkyl, substituted C₂-C₁₂             alkyl, alkenyl, substituted C₄-C₁₂ alkenyl, alkynyl,             substituted alkynyl, aryl, substituted aryl where the             substituent is other than chloro when R₁ and R₂ are ═O,

-   -   -   —CH₂CN, —CH₂CO₂R₁₁, —CH₂COR₁₁, —NHR₁₁ or —NH⁺(R₁₁)₂, where             each R₁l is independently alkyl, alkenyl or alkynyl, each of             which is substituted or unsubstituted, or H;

    -   R₅ and R₆ is each independently H, OH, or R₅ and R₆ taken         together are ═O; and

    -   R₇ and R₈ is each independently H, F, Cl, Br, SO₂Ph, CO₂CH₃, or         SR₁₂,         -   where R₁₂ is H, aryl or a substituted or unsubstituted             alkyl, alkenyl or alkynyl,

    -   or a salt, enantiomer or zwitterion of the compound, or a         compound having the structure

-   -   wherein     -   n is 1-10;     -   Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂,         trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl;     -   Z is

-   -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl,         SO₂R₃₄, NO₂, trifluoromethyl, methoxy, or CO—R₃₄, wherein     -   R₃₄ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl, or a         salt of the compound,         so as to thereby inhibit the aggregation of Tau in the cell.

In an embodiment of the above method, the compound has the structure

-   -   wherein     -   n is 1-9;     -   Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂,         trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl,         SO₂R₃₄, NO₂, trifluoromethyl, methoxy, or CO—R₃₄, wherein     -   R₃₄ is alkyl, alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl.

In another embodiement of the above method, the compound has the structure

-   -   wherein     -   n is 1-8;     -   Y is CH or N;     -   R₂₀ is H or OH;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         C₁-C₆ alkyl or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂, trifluoromethyl, methoxy,         or CO—R₂₆, wherein R₂₆ is alkyl, alkenyl, alkynyl, C₃-C₈         cycloalkyl, or aryl.

In a further embodiment of the above method, the compound has the structure

-   -   wherein     -   n is 1-9;     -   Y is C—R₃₀ or N, wherein R₃₀ is H, OH, SH, F, Cl, SO₂R₂₆, NO₂,         trifluoromethyl, methoxy, or CO—R₂₆, wherein R₂₆ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         H, C₁-C₆ alkyl, or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and         R₂₅, R₃₁, R₃₂, and R₃₃ are each independently H, OH, SH, F, Cl,         trifluoromethyl, methoxy, or CO—R₃₄, wherein R₃₄ is alkyl,         alkenyl, alkynyl, C₃-C₈ cycloalkyl, or aryl; In further         embodiment, the compound has the structure

-   -   wherein     -   n is 1-8;     -   Y is CH or N;     -   R₂₀ is H or OH;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         C₁-C₆ alkyl or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅ is H, OH, SH, F, Cl, trifluoromethyl, methoxy, or CO—R₂₆,         wherein R₂₆ is alkyl, alkenyl, alkynyl, or C₃-C₈ cycloalkyl, or         aryl.

In another embodiment, the compound has the structure

-   -   wherein     -   n is 1-8;     -   Y is CH or N;     -   R₂₀ is H or OH;     -   R₂₁ is H or NR₂₂R₂₃, wherein R₂₂ and R₂₃ are each independently         C₁-C₆ alkyl or C₃-C₈ cycloalkyl;     -   R₂₄ is OH or SH; and     -   R₂₅ is H, OH, SH, F, Cl, trifluoromethyl, methoxy, or CO—R₂₆,         wherein R₂₆ is alkyl, alkenyl, alkynyl, or C₃-C₈ cycloalkyl, or         aryl.

In one embodiment of the foregoing methods, the cell is a neural cell. In another embodiment of the foregoing methods, The cell is in a subject.

In an embodiment of any of the foregoing methods, the compound has structure of Compound 100, Compound 100E, Compound 101, Compound 101E, Compound 102, Compound 102E, Compound 103, Compound 103E, Compound 104, Compound 104E, Compound 105, Compound 105E, Compound 106, Compound 106E, Compound 107, Compound 107E, Compound 108 or Compound 108E.

In an embodiment of any of the foregoing methods, the compound has the structure of Compound 201, Compound 203, Compound 204, Compound 205, Compound 206, Compound 207, Compound 207(a), Compound 208, Compound 209, Compound 210, Compound 211, Compound 212, Compound 213, or Compound 214.

Definitions

Certain embodiments of the disclosed compounds can contain a basic functional group, such as amino or alkylamino, and are thus capable of forming pharmaceutically acceptable salts with pharmaceutically acceptable acids, or contain an acidic functional group and are thus capable of forming pharmaceutically acceptable salts with bases. The instant compounds therefore may be in a salt form. As used herein, a “salt” is a salt of the instant compounds which has been modified by making acid or base salts of the compounds. The salt may be pharmaceutically acceptable. Examples of pharmaceutically acceptable salts include, but are not limited to, mineral or organic acid salts of basic residues such as amines; alkali or organic salts of acidic residues such as phenols. The salts can be made using an organic or inorganic acid. Such acid salts are chlorides, bromides, sulfates, nitrates, phosphates, sulfonates, formates, tartrates, maleates, malates, citrates, benzoates, salicylates, ascorbates, and the like. Phenolate salts are the alkaline earth metal salts, sodium, potassium or lithium. The term “pharmaceutically acceptable salt” in this respect, refers to the relatively non-toxic, inorganic and organic acid or base addition salts of compounds of the present invention. These salts can be prepared in situ during the final isolation and purification of the compounds of the invention, or by separately reacting a purified compound of the invention in its free base or free acid form with a suitable organic or inorganic acid or base, and isolating the salt thus formed. Representative salts include the hydrobromide, hydrochloride, sulfate, bisulfate, phosphate, nitrate, acetate, valerate, oleate, palmitate, stearate, laurate, benzoate, lactate, phosphate, tosylate, citrate, maleate, fumarate, succinate, tartrate, napthylate, mesylate, glucoheptonate, lactobionate, and laurylsulphonate salts and the like. For a description of possible salts, see, e.g., Berge et al. (1977) “Pharmaceutical Salts”, J. Pharm. Sci. 66:1-19.

As used herein, “therapeutically effective amount” means an amount sufficient to treat a subject afflicted with a disease (e.g. a neurodegenerative disease) or to alleviate a symptom or a complication associated with the disease.

As used herein, a “neurodegenerative disease” refers to a disease in which degeneration occurs of either gray or white matter, or both, of the nervous system. Thus, such a disease can be diabetic neuropathy, senile dementias, Alzheimer's disease, Mild Cognitive Impairment (MCI), dementia, Lewy Body Dementia, Frontal Temporal Lobe dementia, Parkinson's Disease, facial nerve (Bell's) palsy, glaucoma, Huntington's chorea, amyotrophic lateral sclerosis (ALS), status epilepticus, non-arteritic optic neuropathy, intervertebral disc herniation, vitamin deficiency, prion diseases such as Creutzfeldt-Jakob disease, carpal tunnel syndrome, peripheral neuropathies associated with various diseases, including but not limited to, uremia, porphyria, hypoglycemia, Sjorgren Larsson syndrome, acute sensory neuropathy, chronic ataxic neuropathy, biliary cirrhosis, primary amyloidosis, obstructive lung diseases, acromegaly, malabsorption syndromes, polycythemia vera, IgA and IgG gammapathies, complications of various drugs (e.g., metronidazole) and toxins (e.g., alcohol or organophosphates), Charcot-Marie-Tooth disease, ataxia telangectasia, Friedreich's ataxia, amyloid polyneuropathies, adrenomyeloneuropathy, Giant axonal neuropathy, Refsum's disease, Fabry's disease and lipoproteinemia.

As used herein, “tauopathies” refers to a class of neurodegenerative diseases which result from aggregation of tau protein in neurofibrillary tangles. Examples of tauopathies include, but are not limited to, Alzheimer's disease, Frontotemproal dementia (Pick's disease), Progressive Supranuclear Palsy, and Corticobasal degeneration.

As used herein, “treating” means slowing, stopping or reversing the progression of a disease, particularly a neurodegenerative disease.

As used herein, “zwitterion” means a compound that is electrically neutral but carries formal positive and negative charges on different atoms. Zwitterions are polar, have high solubility in water have poor solubility in most organic solvents.

The compounds disclosed herein may also form zwitterions. For example, a compound having the structure

may also for the following zwitterionic structure

where X is as defined throughout the disclosures herein.

As used herein, “alkyl” is intended to include both branched and straight-chain saturated aliphatic hydrocarbon groups having the specified number of carbon atoms. Thus, C₁-C_(n) as in “C₁-C_(n) alkyl” is defined to include groups having 1, 2, . . . , n−1 or n carbons in a linear or branched arrangement, and specifically includes methyl, ethyl, propyl, butyl, pentyl, hexyl, and so on. An embodiment can be C₁-C₁₂ alkyl. “Alkoxy” represents an alkyl group as described above attached through an oxygen bridge.

The term “alkenyl” refers to a non-aromatic hydrocarbon radical, straight or branched, containing at least 1 carbon to carbon double bond, and up to the maximum possible number of non-aromatic carbon-carbon double bonds may be present. Thus, C₂-C_(n) alkenyl is defined to include groups having 1, 2, . . . , n−1 or n carbons. For example, “C₂-C₆ alkenyl”, means an alkenyl radical having 2, 3, 4, 5, or 6 carbon atoms, and at least 1 carbon-carbon double bond, and up to, for example, 3 carbon-carbon double bonds in the case of a C₆ alkenyl, respectively. Alkenyl groups include ethenyl, propenyl, butenyl and cyclohexenyl. As described above with respect to alkyl, the straight, branched or cyclic portion of the alkenyl group may contain double bonds and may be substituted if a substituted alkenyl group is indicated. An embodiment can be C₂-C₁₂ alkenyl.

The term “alkynyl”, refers to a hydrocarbon radical straight or branched, containing at least 1 carbon to carbon triple bond, and up to the maximum possible number of non-aromatic carbon-carbon triple bonds may be present. Thus, C₂-C_(n) alkynyl is defined to include groups having 1, 2, . . . , n−1 or n carbons. For example, “C₂-C₆ alkynyl” means an alkynyl radical having 2 or 3 carbon atoms, and 1 carbon-carbon triple bond, or having 4 or 5 carbon atoms, and up to 2 carbon-carbon triple bonds, or having 6 carbon atoms, and up to 3 carbon-carbon triple bonds. Alkynyl groups include ethynyl, propynyl and butynyl. As described above with respect to alkyl, the straight or branched portion of the alkynyl group may contain triple bonds and may be substituted if a substituted alkynyl group is indicated. An embodiment can be a C₂-C_(n) alkynyl.

As used herein, “aryl” is intended to mean any stable monocyclic or bicyclic carbon ring of up to 10 atoms in each ring, wherein at least one ring is aromatic. Examples of such aryl elements include phenyl, naphthyl, tetrahydro-naphthyl, indanyl, biphenyl, phenanthryl, anthryl or acenaphthyl. In cases where the aryl substituent is bicyclic and one ring is non-aromatic, it is understood that attachment is via the aromatic ring. The substituted aryls included in this invention include substitution at any suitable position with amines, substituted amines, alkylamines, hydroxys and alkylhydroxys, wherein the “alkyl” portion of the alkylamines and alkylhydroxys is a C₂-C_(n) alkyl as defined hereinabove. The substituted amines may be substituted with alkyl, alkenyl, alkynl, or aryl groups as hereinabove defined.

The alkyl, alkenyl, alkynyl, and aryl substituents may be unsubstituted or unsubstituted, unless specifically defined otherwise. For example, a (C₁-C₆) alkyl may be substituted with one or more substituents selected from OH, oxo, halogen, alkoxy, dialkylamino, or heterocyclyl, such as morpholinyl, piperidinyl, and so on.

In the compounds of the present invention, alkyl, alkenyl, and alkynyl groups can be further substituted by replacing one or more hydrogen atoms by non-hydrogen groups described herein to the extent possible. These include, but are not limited to, halo, hydroxy, mercapto, amino, carboxy, cyano and carbamoyl. The term “substituted” as used herein means that a given structure has a substituent which can be an alkyl, alkenyl, or aryl group as defined above. The term shall be deemed to include multiple degrees of substitution by a named substitutent. Where multiple substituent moieties are disclosed or claimed, the substituted compound can be independently substituted by one or more of the disclosed or claimed substituent moieties, singly or plurally. By independently substituted, it is meant that the (two or more) substituents can be the same or different.

As used herein, “administering” an agent may be performed using any of the various methods or delivery systems well known to those skilled in the art. The administering can be performed, for example, orally, parenterally, intraperitoneally, intravenously, intraarterially, transdermally, sublingually, intramuscularly, rectally, transbuccally, intranasally, liposomally, via inhalation, vaginally, intraoccularly, via local delivery, subcutaneously, intraadiposally, intraarticularly, intrathecally, into a cerebral ventricle, intraventicularly, intratumorally, into cerebral parenchyma or intraparenchchymally.

The following delivery systems, which employ a number of routinely used pharmaceutical carriers, may be used but are only representative of the many possible systems envisioned for administering compositions in accordance with the invention.

Injectable drug delivery systems include solutions, suspensions, gels, microspheres and polymeric injectables, and can comprise excipients such as solubility-altering agents (e.g., ethanol, propylene glycol and sucrose) and polymers (e.g., polycaprylactones and PLGA's).

Implantable systems include rods and discs, and can contain excipients such as PLGA and polycaprylactone.

Oral delivery systems include tablets and capsules. These can contain excipients such as binders (e.g., hydroxypropylmethylcellulose, polyvinyl pyrilodone, other cellulosic materials and starch), diluents (e.g., lactose and other sugars, starch, dicalcium phosphate and cellulosic materials), disintegrating agents (e.g., starch polymers and cellulosic materials) and lubricating agents (e.g., stearates and talc).

Transmucosal delivery systems include patches, tablets, suppositories, pessaries, gels and creams, and can contain excipients such as solubilizers and enhancers (e.g., propylene glycol, bile salts and amino acids), and other vehicles (e.g., polyethylene glycol, fatty acid esters and derivatives, and hydrophilic polymers such as hydroxypropylmethylcellulose and hyaluronic acid).

Dermal delivery systems include, for example, aqueous and nonaqueous gels, creams, multiple emulsions, microemulsions, liposomes, ointments, aqueous and nonaqueous solutions, lotions, aerosols, hydrocarbon bases and powders, and can contain excipients such as solubilizers, permeation enhancers (e.g., fatty acids, fatty acid esters, fatty alcohols and amino acids), and hydrophilic polymers (e.g., polycarbophil and polyvinylpyrolidone). In one embodiment, the pharmaceutically acceptable carrier is a liposome or a transdermal enhancer.

Solutions, suspensions and powders for reconstitutable delivery systems include vehicles such as suspending agents (e.g., gums, zanthans, cellulosics and sugars), humectants (e.g., sorbitol), solubilizers (e.g., ethanol, water, PEG and propylene glycol), surfactants (e.g., sodium lauryl sulfate, Spans, Tweens, and cetyl pyridine), preservatives and antioxidants (e.g., parabens, vitamins E and C, and ascorbic acid), anti-caking agents, coating agents, and chelating agents (e.g., EDTA).

It is understood that substituents and substitution patterns on the compounds of the instant invention can be selected by one of ordinary skill in the art to provide compounds that are chemically stable and that can be readily synthesized by techniques known in the art from readily available starting materials. If a substituent is itself substituted with more than one group, it is understood that these multiple groups may be on the same carbon or on different carbons, so long as a stable structure results.

The compounds disclosed herein (Compounds 100-108, Compounds 100E to 108E, Compound 201, Compounds 203-214 and Compound 207(a)) were obtained from Lixte Biotechnology Holdings, Inc., 248 Route 25A, No. 2, East Setauket, N.Y.

Discussion

The compounds described herein are useful for the prevention and/or treatment of neurodegenerative conditions including Alzheimer's disease, Parkinson's disease, motor neuron diseases such as amyotrophic lateral sclerosis, and other neurodegenerative diseases collectively known as tauopathies.

Several of the compounds inhibit protein phosphatase 2A. These include Compounds 100, 102, 103, 104, 105, 106, 107, 108, 111, the structures of which are shown in Table 1. These compounds differ in substituents on portions of the core molecule Compound 100. These compounds show dose dependent inhibition of a broad spectrum of human cancer cell lines in vitro including SH-SY5Y, a dopaminergic neuronal line, frequently used as a model for assessing pharmacologic interventions relevant to human neuronal cells. Given intraperitoneally, these compounds enter the brain of the normal mouse as demonstrated by increased acetylation of histone 3 and 8.

The compounds increase the phosphorylation of several regulatory proteins including Akt. At low doses that are non-toxic to mice, these compounds slightly stimulate cell proliferation and increases phosphorylation of Akt in human cancer cell lines tested including SH-SY5Y. When given intraperitoneally to normal mice, Compound 100 and Compound 102 also increased Akt phosphorylation in the cell lines tested, growing as xenografts in SCID mice, as set forth in the examples herein.

Because the Compound-100 series of drugs increase cellular phosphorylated Akt at low non-toxic doses and also increase acetylation of histones in neurons of the intact animal, these compounds are useful for the treatment of neurodegenerative diseases, particularly Alzheimer's disease and all other tauopathies. While each of the compounds tested increase Akt phosphorylation of multiple tumor cell lines, they also increase Akt phosphorylation of the neuroblastoma cell line SH-SY5Y, a model of dopamine neurons.

The results with Compound 100 and Compound 102 show that each of these has properties that enhance their entry into the brain. Thus, these drugs are neuroprotective and useful for the prevention and/or treatment of neurodegereratve disease. The mechanism by which the Compound 100 series of compounds exert their neuroprotective effect may be by increasing the intra-neuronal cell activity of Akt-1 and enhancing the phosphorylation of GSK-3B. Each of these compounds when given by intraperitoneal injection, increase Akt phosphorylation in mouse neurons. This increase in Akt phosphorylation is associated with an increase in the phosphorylation of GSK-3β. Increased phosphorylation of GSK-3β is known to decrease its activity. Therefore, chronic suppression of GSK-3β activity by compound 100 homologs may reduce tau phosphorylation. Reduction in tau phosphorylation reduces the formation of paired helical filaments, an intervention that should lessen the progression of tauopathies including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and other rarer neurodegenerative diseases characterized by abnormal depositions of tau molecules.

The compound 200 series, which include compounds 201, 207(a) and 203-214, the structures of which are shown in Table 2, are HDAC inhibitors.

TABLE 1 Compouns 100-108 and 111 Compound 100

Compound 100E

Compound 101

Compound 101E

Compound 102

Compound 102E

Compound 103

Compound 103E

Compound 104

Compound 104E

Compound 105

Compound 105E

Compound 106

Compound 106E

Compound 107

Compound 107E

Compound 108

Compound 108E

Compound 111

TABLE 2 Compound Structure 201

203

204

205

206

207

207a

208

209

210

211

212

213

214

EXPERIMENTAL DETAILS First Series of Experiments

In Vivo Experiments

Human medulloblastoma DAOY cells were implanted subcutaneously in SCID mice. Mice were then treated with 0.03 mg/20 gram mouse with Compound 100 or vehicle alone. After 4 hours and 24 hours, western blots were made for phosphorylated Akt (p-Akt), total Akt, and beta actin. Control cells at both time points had only trace amount of p-Akt and substantial amounts of total Akt and beta actin. Exposure to compound 100 revealed induction of p-Akt and an increase in total Akt relative to beta actin, as shown in FIG. 3.

Human glioblastoma U87 cells were implanted subcutaneously in SCID mice. Mice were then treated with 0.03 mg/20 gram mouse with Compound 100 or vehicle alone. After 4 hours, western blots were made for p-Akt, total Akt, and beta actin. Control cells showed only trace amounts of p-Akt and substantial amounts of total Akt and beta actin. Exposure to Compound 100 revealed induction of p-Akt and an increast in total Akt relative to beta actin, as shown in FIG. 5.

Normal mice were treated with Compound 100 or Compound 102 at a dose of 0.03 mg/20 gram mouse, or with vehicle. After 4 hours of exposure, treated and control animals were sacrificed and western blots for acetylated histone 3 and histone 4 were made. As showing in FIG. 6, both drugs increased acetylation of the histones compared to control tissue.

In Vitro Experiments:

Medulloblastoma cells, DAOY, were grown in culture and exposed to Compound 100, Compound X or vehicle alone. After 4 hours western blots were made for p-Akt, total Akt and beta actin. Control cells showed only trace amounts of p-Akt and substantial amounts of total Akt and beta actin. Exposure to the control agent Compound 205, an investigational histone deacetylase inhibitor, had little effect. Exposure to Compound 100 revealed induction of p-Akt and an increase in total Akt relative to beta actin.

Human glioblastoma cells, U87, were grown in culture and exposed to Compound 100 or vehicle alone. After 4 hours, western blots were made for p-Akt, total Akt, and beta actin. Control cells showed only trace amounts of p-Akt and substantial amounts of total Akt and beta actin. Exposure to Compound 100 revealed induction of p-Akt and an increase in total akt relative to beta actin, as shown in FIG. 4.

Neuroprotective and neurotrophic effects of a novel HDAC inhibitor, compound 201, and a novel protein phosphatase 2A inhibitor, compound 102, on primary rat cortical neurons.

The effects of two novel compounds, compound 201, a class I and II HDAC inhibitor (HDACi), and compound 102, a protein phosphatase 2A inihibitor (PP2Ai), on neuronal cell characteristics including physiological responses to signalling agents, differentiation and maturation in culture, and survival following environmental stress were investigated. Neurite extension was evaluated after Calcein staining using commercially available software. Exposure to either compound 201 or compound 102 at 250 and 500 nM resulted in increased total neurite outgrowth and increased process length and then was evaluated for their ability to sustain neuron integrity over time after exposure to stress.

Neurons were chronically or acutely treated with each compound and exposed to environmental stress (replacement of the culture medium with a saline PBS based solution for one hour followed by removal of the PBS medium and restoration of standard neuronal culture medium) and then observed for survival (FIG. 6). Compound 201 displayed marked neurotrophic effects as evidenced by maintenance for up to 21 days neuronal cell numbers. In contrast, cells exposed to either DMSO (the vehicle used for the compounds) or just saline showed a 3.5 fold reduction in cell numbers (FIG. 7). Compound 102 had little effect on cell number. To assess the effects of compound 102 and compound 201, independently, on neuronal function, the ability of the neurons in a culture dish to respond to exposure to glutamate was studied. In vitro, neurons respond to glutamate with the activation of several receptors associated with different transducing mechanisms. The assortment of glutamate sensitive receptors in a given neuronal population depends on maturation and differentiation. After seven days in culture, there is an assortment of glutamate receptors, including the AMPA/Kainate and NMDA receptors. AMPA/Kainate receptors are in general maximally expressed in the first few days in vitro followed by a gradual decline, while NMDA receptor expression increases over time, reaching a maximum after 7 days in vitro. AMPA/Kainate responses to exposure to glutamate as measured by calcium flux are characterized by fast desensitization (i.e. very little measurable calcium increase), while NMDA responses are characterized by an elevation of calcium concentration that persists as long as glutamate is applied. In the absence of test drug, there was variability in glutamate responsiveness dependent on NMDA receptor expression. A typical response of neurons in culture to glutamate characteristic of the NMDA receptors consists of a rapid increase and a high plateau phase of calcium (FIGS. 8-10). Repeat experiments showed variability in the extent of this response indicating that the time-point in culture is a moment at which NMDA receptor expression is variable. Exposures to 500 nM compound 201 (FIGS. 11-14) and, independently, to 500 nM compound 102 (FIGS. 15-18) for 24 h prior exposure to glutamate, however, were associated with a statistically significant increase in the NMDA type response to glutamate (p<=0.001), particularly in neurons showing the smallest response to glutamate (FIGS. 11-14). This modulation is compatible with a positive neurotrophic effect of compound 201. A similar smaller but statistically significant effect (p<=0.01) was associated with compound 102 (FIG. 19).

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1. A method for reducing the amount of active GSK-3B or increasing the amount of phosphorylated Akt in a neural cell comprising contacting the cell with an effective amount of a compound having the structure

wherein bond α is present or absent; R₁ and R₂ is each independently H, O⁻ or OR₉, where R₉ is H, alkyl, alkenyl, alkynyl or aryl, or R₁ and R₂ together are ═O; R₃ and R₄ are each different, and each is OH, O⁻, OR₉, SH, S⁻, SR₉,

where X is O, S, NR₁₀, or N⁺R₁₀R₁₀, where each R₁₀ is independently H, alkyl, substituted C₂-C₁₂ alkyl, alkenyl, substituted C₄-C₁₂ alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl where the substituent is other than chloro when R₁ and R₂ are ═O,

—CH₂CN, —CH₂CO₂R₁₁, —CH₂COR₁₁, —NHR₁₁ or —NH⁺(R₁₁)₂, where each R₁₁ is independently alkyl, alkenyl or alkynyl, each of which is substituted or unsubstituted, or H; R₅ and R₆ is each independently H, OH, or R₅ and R₆ taken together are ═O; and R₇ and R₈ is each independently H, F, Cl, Br, SO₂Ph, CO₂CH₃, or SR₁₂, where R₁₂ is H, aryl or a substituted or unsubstituted alkyl, alkenyl or alkynyl, or a salt, enantiomer or zwitterion of the compound so as to thereby reduce the amount of GSK-3B or increase the amount of phosphorylated Akt in the neural cell.
 2. The method of claim 1, wherein R₄ is

where X is O, NR₁₀, N⁺R₁₀R₁₀ where each R₁₀ is independently H, alkyl, substituted C₂-C₁₂ alkyl, alkenyl, substituted C₄-C₁₂ alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl where the substituent is other than chloro when R₁ and R₂ are ═O,

—CH₂CN, —CH₂CO₂R₁₁, —CH₂COR₁₁, —NHR₁₁ or —NH⁺(R₁₁)₂, where R₁₁ is H or alkyl.
 3. The method of claim 1, wherein bond α is present.
 4. The method of claim 1, wherein bond α is absent.
 5. The method of claim 1, wherein the compound has the structure


6. The method of claim 5, wherein the compound has the structure 